Wheel hub

ABSTRACT

A wheel hub ( 10 ), primarily for a wheelchair wheel, can be manually operated by rotating a cover ( 168 ) to give three different operating states for the wheel which includes the hub. In the first position, the wheel is free to rotate relative to the chair. In the second position, the wheel is locked to the chair, i.e. the chair is braked. In the third position, the wheel can turn in the direction corresponding to forward motion of the chair, but cannot rotate in the opposite direction. This prevents the wheelchair from undesired backward rolling movement.

This invention relates to a wheel hub, particularly but not exclusivelyto a hub for a wheelchair wheel.

Wheelchairs are used by physically handicapped people to give themmobility. They are conventionally propelled by the user who rotateshandwheels fixed to the road wheels. The handwheels are centred on theaxis of rotation of the road wheels. In most cases, the handwheels arerigidly fixed to the road wheels so that one revolution of the handwheels equates to one revolution of the road wheels.

When the wheelchair is stationary, a brake should be applied to preventthe wheelchair from moving unintentionally. It is known to use brakeswhich press against the tyre of the road wheel.

EP-A-0 220 734 describes a wheelchair brake which can be set in threedifferent positions. In one position there is no restraint on the wheelwhich can rotate freely in either direction. In a second position thewheel can only rotate in one (forwards) direction. In the thirdposition, the wheel is braked and cannot rotate at all.

According to the invention, there is provided a wheel hub whichcomprises a spindle, a sleeve rotatable relative to the spindle througha bearing, and a manually operable device which has three operatingpositions, a first of which allows free rotation between the spindle andthe sleeve, a second of which locks the spindle to the sleeve to effecta braking action, and a third of which engages a ratchet arrangementwhich allows the spindle to rotate relative to the sleeve in onedirection only, characterised in that the manually operable device isfitted on the hub. Fitting the manually operable device on the huballows the wheel to be easily attached and reattached to the wheelchairframe without having to dismantle the mechanism which controls the wheelrotation.

The wheel hub is particularly intended for use on the wheels of awheelchair. A hub will be fitted at the centre of each of the maindriving wheels of the chair.

The ratchet arrangement produces a feature referred to as‘anti-rollback’. In other words, this position is engaged by the userwhen the wheelchair is going uphill and prevents the wheel chair fromrolling back down the hill if the user stops turning the handwheels.

The selection of one of the three positions is preferably carried out bymanipulating a selector mounted on the hub itself. The selector may be arotatable disc mounted for rotation about an axis coincident with thehub axis. The selector may have a central position corresponding to thefirst operating position, with the second and third operating positionsbeing reached by rotating the selector in one direction for the secondoperating position and in the opposite direction for the third operatingposition.

The disc can have a radially outwardly extending lever to enable it tobe turned, or may have a circumferential surface modified to allow it tobe gripped and turned. For example the surface, may be provided with arubber ring, or may be formed with a type of knurling or similar toincrease grip.

The spindle is preferably provided with a mounting bracket by which itcan be non-rotatably mounted on the wheelchair frame. This bracket mayhave axially extending pins or sockets which engage with axiallyextending sockets or pins on the hub. The hub is preferably providedwith a quick detachment mechanism enabling the hub (together with awheel attached to the hub) to be quickly and easily detached from thewheelchair frame. The spindle may have a radial projection at its innerend which can be retracted to enable the spindle to be inserted in orwithdrawn from the mounting bracket. When the projection is extended,relative axial movement between the spindle and the mounting bracketcannot take place, and when the pins and sockets are engaged with oneanother rotational movement between the spindle and the bracket cannottake place.

The manually operable device preferably comprises a splined annularsurface on the spindle surrounded by a body on the sleeve which has arecess in which the splined surface lies so that the body is free torotate relative to the spindle, and to the splined surface on thespindle, when the hub takes up the first operating position, the devicealso including a first pin or pins, fixed against rotation relative tothe sleeve, which can be moved from a retracted position into the pathof relative rotational movement between the body and the splined annularsurface to engage with the splines and to thus prevent rotation of thesleeve relative to the spindle (the second operating position) and asecond pin or pins, also fixed against rotation relative to the sleevewhich can be moved into the path of relative rotational movement betweenthe body and the splined annular surface, when the first pin or pins isin a retracted position, to engage with the splines and to preventrotation of the sleeve in one rotational direction relative to thespindle but to allow rotation in the opposite rotation direction.

The first pin or pins may have square end profiles which engage betweensplines on the splined surfaces and the second pin or pins may have endprofiles with one square face and one ramp face which engage betweensplines on the splined surfaces, so that the square face preventsrotation of the sleeve in one rotational direction relative to thespindle and the ramp face allows rotation in the opposite rotationdirection. The first pin or pins are preferably diametrically opposite(referred to the spindle axis) to the second pin or pins.

In one embodiment, the body on the sleeve has radially extendingpassages communicating with the recess and the pins are radially movablepins which can move in and out of the recess to engage, one at a time,with the splined surface. The radially movable pins have lateral lugswhich engage in cam tracks inside the selector so that movement of theselector in one rotational direction extends the first pins and movementin the opposite rotational direction extends the second pins.

In another embodiment, the body on the sleeve comprises a radiallymovable slide plate moving between two fixed parallel slide guides suchthat the plate can move radially but cannot rotate relative to theguides, the recess being provided in the slide plate and the pine beingformed integrally with the plate at opposite regions of thecircumference of the recess. Leaf springs mounted internally on theselector bias the opposite ends of the slide plate and, the slide plateends and the leaf springs are designed so that movement of the selectorin each direction causes the leaf springs to ride over a none on theslide plate so that the selector is held in one or other ed positionuntil the selector in manually operated to a different position.

There may be two first pins and two second pins.

The invention also extends to a wheelchair wheel having a hub as setforth above, and to a wheelchair having wheels of this type.

The invention will now be further described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is a side view, partly in section, of a hub in accordance withthe invention;

FIG. 2 is an exploded view of a manually operable changing deviceforming part of the hub of FIG. 1;

FIG. 3 is a side view of a spindle;

FIG. 4 is an end view of the spindle of FIG. 3;

FIG. 5 in a side view of a mounting collar;

FIG. 6 is an end view of the collar of FIG. 5;

FIG. 7 is a front view of a cover for the mechanism of FIG. 2;

FIG. 8 is a cross-section through the cover of FIG. 7;

FIG. 9 is an rear view of the cover shown in FIG. 7, showing theinterior of the cover;

FIG. 10 is a front view of a centre disc forming part of the mechanismof FIG. 2;

FIG. 11 is a side view on the arrow A of the disc of FIG. 10;

FIG. 12 shows a ratchet pin;

FIG. 13 is a top view of a lock pin;

FIG. 14 is a side view of the lock pin shown in FIG. 13;

FIG. 15 is a perspective view, partly cut away, of a second embodimentof hub in accordance with the invention;

FIG. 16 is a plan view of the hub of FIG. 15 showing additionalcomponents; and

FIG. 17 is an exploded view of a spindle for use with the hub of theinvention.

FIG. 1 show a hub assembly generally designated 10 with a hub body 28.The hub body is connected to a wheel rim (not shown) by spokes 12 in aconventional manner. The hub has an axis of rotation at 14, and ismounted for rotation relative to a wheelchair frame 16, only a smallpart of which is show in the drawing.

The hub assembly includes a collar 1 (FIGS. 5 and 6) with a shoulder 20,a hollow shaft 22 and a threaded region 24. The shaft 22 is passedthrough the wheelchair frame 16, and a nut 26 is tightened onto thethreaded portion 24 to fix the collar 16 to the wheelchair frame 16.

As a separate component, the hub body 28 is fitted onto a spindle 30(FIG. 3) and secured on the spindle between a flange 32 and a nut 34.The body 28 has an integral bearing which allows the body to rotaterelative to the spindle 30. The assembly of the wheel with spokes 12,body 28 and spindle 30 can then be mounted in the collar 18 by insertingthe left hand end 36 of the spindle into the bore 22 of the collar. Aspring loaded retention hall 38 can be pressed back into the spindle 30to allow the spindle to pass through the bore 22. The spindle will beprevented from rotating relative to the collar 18 by the engagement ofpins 40 on the shoulder 32 in holes 42 on the shoulder 20. There may befor example three pine 40 on the spindle and six holes 42 on theshoulder, so that the two can engage in a number of different angularpositions.

The mechanism by which the wheel and the spindle can be withdrawn fromthe collar 18 is similar to that described in U.S. Pat. No. 5,727,850. Apush button 44 on the end of a rod 46 can be pushed in to release radialpressure on the projecting retention ball 38, and whilst this pressureis maintained on the push button, the spindle 30 can be withdrawn fromthe collar 18.

The parts of the hub which control its operation will now be described.

A part 50 of the nut 34 has a raised circumference with a splined orcastellated rim. When the nut 34 is tightened to secure the body 28, thenut 34 and the rim 50 are fixed to the spindle 30. An outer annular disc52 (FIG. 2) is fixed to the flange 54 of the hub body 28. Located inradial passages in the annular body 52 are two pins 56 and 58. One pin56 is responsible for braking the wheel and the other pin 58 isresponsible for providing an anti-rollback feature. The pins arediametrically opposite to one another.

Under normal conditions, both pins 56 and 58 are housed within theirpassages 60, 62 in the annular body 52 and provide no resistance to freerelative rotation of the castellated rim 50 inside the body 52. Thewheel in therefore free to rotate on its spindle in either direction.

In order to brake the wheel, the pin 56 has to move radially inwards sothat its tip 64 engages between two of the castellations of the rim 50,and a spring is positioned behind the pin to drive the pin inwards. Inthis position, relative movement between the rim 50 and the body 52 islocked and there can then be no movement between the wheel and thespindle 30. In other words the wheel is fully braked.

If the pin 56 is withdrawn and in its place the pin 58 is driven inwards(likewise by a spring), then the shape of the tip 66 of the pin 58engaging against the teeth 50 will allow rotation of the wheel in onedirection, but will prevent rotation in the opposite direction, in themanner of a ratchet.

In order to move either one or the other of the pit 56, 58 in the mannerdescribed, a cover disc 68 is used. The pins 56, 58 are controlled bymovable pegs 70 which extend axially through slots 72 through the wallsof the passages 60, 62 and into the ping 56,58 (See FIG. 14). The topends of these pegs 70 engage in tracks 74, 76 on the inside of the coverdisc 68. The location of these tracks 74, 76 is indicated in dottedlines in FIG. 2 and can be seen clearly in FIGS. 8 and 9 which show theinside of the disc 68. It will be seen that the tracks 74, 76 have acentre position; extending in one direction from this centre position isa track region of constant radius and extending in the other directionis a track region where the radius of the track continually reduces.

FIG. 2 illustrates the situation where the cover disc 68 is in itsmiddle position relative to the annular body 52 and where the pins 56and 58 are not activated. Turning the cover disc 68 in one directionrelative to the annular body 52 causes one of the pegs 70 to moveradially inwards and to force the corresponding pin 56, 58 inwards toengage with the teeth 50. Because the corresponding region of theopposite track is of constant radius, there is no effect on the positionof the opposite pin.

Rotating the cover disc in the opposite direction however producesmovement of the opposite pin.

Both pins 56 and 58 are spring-loaded in a radially inward direction,and are held out of engagement, against the spring pressure by theengagement of the pegs 70 in the tracks 74, 76.

On the outside of the cover disc 68, there in a scalloped rim 80 toallow the cover disc to be gripped by the user so that it can be turnedeither clockwise or anti-clockwise, depending on the function which isto be engaged. However the cover disc 60 has no projecting parts, sothat braking and anti-rollback functions cannot be accidentally engaged.

FIG. 15 shows an alternative construction. In this embodiment, theannular disc 52 of FIG. 2 in replaced by two diametrically appositeguide bodies 152 which have parallel guide surfaces 155 for a slidablelock member 153. The guide bodies 152 are fixed to, or are made integralwith the flange 154 of the hub body. For example, the flange 154 and theguide bodies may be made as a single casting.

The lock member 153 a central aperture 157 within which a splined wheel150 (fast with the spindle 30,130) is received. In the middle positionshown in FIG. 16, the wheel 150, and thus the spindle on which it ismounted, is free to rotate relative to the flange 154/guide bodies 152.

The aperture 157 of the lock member has, at one point around itscircumference, two square profile teeth 164, the profiles of these teethmatching the profiles of the splines on the wheel 150. At an oppositepoint, the lock member has two ratchet teeth 166. The aperture 157 hasflattened portions at 159 which separate the two sets of teeth.

It will be clear from FIG. 16 that the lock member can be moved to theright from its freewheeling position shown in the Figure until the teeth164 engage the splines. The lock member will then be rotationally lockedto the wheel 150 and the spindle 130. Attempted rotation of the spindleand splined wheel 150 will then also require rotation of the lockmember, but such rotation will be blocked by abutment between theparallel surfaces of the lock member and the guide bodies 152. The wheelis therefore locked in this position.

In a similar manner, movement of the lock member 153 to the left willbring the ratchet teeth 166 into engagement with the splines of thewheel 150, and, as previously described, the engagement between theteeth and the splines will allow relative rotation in one direction butnot in the opposite direction. Thus an anti-roll-back facility isachieved.

Movement of the lock member 153 is controlled by two leaf springs161,163 and a cover 168. The leaf springs (which are not shown in FIG.15) are fixed on the inside of a rim 169 of the cover 168, are mirrorimages of one another and are stressed against the ends of the lockmember 153. In the middle position shown in FIG. 16, the springs are inbalance, each exerting the same force on the lock member such that thelock member stays in its central position.

The end profiles 171,173 of the lock member 153 are designed tocooperate with the springs 161 so that

as the cover is turned clockwise (FIG. 16) a larger diameter part of theend profile 171 presses against the spring 161 which increase thepressure on the lock member pushing it to the right

at the opposite end of profile 173, the spring 163 first rides over thenose 175 and then falls into a smaller diameter part of the end profile173. The force being exerted by the spring 161 is thus greater than thatexerted by spring 163, and the lock member is moved to the right intothe locked or braking position.

because the spring 163 has passed the nose 175, the cover 168 and thelock member will be held in this position. To return to the middleposition, rotational force has to be applied again to the cover to makethe spring 163 ride back over the nose 175.

In order to achieve the anti-rollback position, the same sequence isfollowed, but the initial Station of the cover 168 is in ananti-clockwise direction.

In comparison with the embodiment of FIGS. 2 and 10 to 14, thisembodiment has fewer components and thus is easier and cheaper to bothmanufacture and assemble. The locking member 153 can be formed from anextrusion having a cross-sectional shape as shown, the locking membersthen constituting slices cut from the extruded length.

FIGS. 17 and 18 show a modified form of spindle 130. At the right handend, the hollow spindle has a flat 181 onto which the splined wheel 150is force-fitted. The D-shape ensures that there is no relative rotationbetween the wheel and the spindle. Instead of thin shape, there could bemating splines on the end of the spindle 130 and on the internaldiameter of the wheel 150. A short length of thread 183 is provided toenable a lock-nut to be fitted, if necessary.

The other end of the spindle fits within a bore 123 in a collar liewhich is of a similar form and function to the collar 18 which hasalready been described. The spindle has a shoulder 132 which mates witha socket 120 on the end of the collar. The socket has a diametral slot123 which receives the shoulder 132. The slot 123 has an upstanding pin125 and the shoulder has corresponding holes 127 When the collar andspindle are correctly assembled, the pin 125 locates in one of the holes127. The pin and the holes can be off-centre, and the collars can behanded so that a heel intended for the right hand side of a wheelchaircannot be fitted to the left hand side, and vice versa.

What is claimed is:
 1. A wheel hub which comprises a spindle, a sleeverotatable relative to the spindle, a bearing between the sleeve and thespindle to allow said relative rotation, and a manually operable devicewhich has three operating positions, a first of which allows freerotation between the spindle and the sleeve, a second of which locks thespindle to the sleeve to effect a braking action, and a third of whichengages a ratchet arrangement which allows the spindle to rotaterelative to the sleeve in one direction only, characterised in that themanually operable device is fitted on the hub and a splined annularsurface on the spindle surrounded by a body on the sleeve which has arecess in which the splined surface lies so that the body is free torotate relative to the spindle and the splined surface on the spindle,when the hub takes up the first operating position, the device alsoincluding a first pin or pins, fixed against rotation relative to thesleeve, which can be moved from a retracted position into the path ofrelative rotational movement between the body and the splined annularsurface to put the hub into the second operating position and to engagewith the splines and to thus prevent rotation of the sleeve relative tothe spindle and a second pin or pins, also fixed against rotationrelative to the sleeve, which can be moved into the path of relativerotational movement between the body and the splined annular surface,when the first pin or pins is in a retracted position, to put the hubinto the third operating position and to engage with the splines and toprevent rotation of the sleeve in one rotational direction relative tothe spindle but to allow rotation in the opposite rotation direction. 2.A wheel hub as claimed in claim 1, wherein the selection of one of thethree positions is carried out by manipulating a selector mounted on thehub itself.
 3. A wheel hub as claimed in claim 2, wherein the selectoris a rotatable disc mounted for rotation about an axis coincident withthe hub axis.
 4. A wheel hub as claimed in claim 3, wherein the selectorhas a central position corresponding to the first operating position,with the second and third operating positions being reached by rotatingthe selector in one direction for the second operating position and inthe opposite direction for the third operating position.
 5. A wheel hubas claimed in claim 3, wherein the disc has a radially outwardlyextending lever to enable it to be turned.
 6. A wheel hub as claimed inclaim 3, wherein the disc has a circumferential surface modified toallow it to be gripped and turned.
 7. A wheel hub as claimed in claim 6,wherein the circumferential surface is provided with a rubber ring.
 8. Awheel hub as claimed in claim 6, wherein the circumferential surface isformed with a type of knurling or similar to increase grip.
 9. A wheelhub as claimed in claim 1, adapted for use on the wheels of awheelchair.
 10. A wheel hub as claimed in claim 9, wherein the spindleis provided with a mounting bracket by which it can be non-rotatablymounted on a wheelchair frame.
 11. A wheel hub as claimed in claim 10,wherein the bracket has axially extending pins or sockets which engagewith axially extending sockets or pins on the hub.
 12. A wheel hub asclaimed in claim 9, provided with a quick detachment mechanism enablingthe hub together with a wheel attached to the hub- to be quickly andeasily detached from the wheelchair frame.
 13. A wheel hub as claimed inclaim 12, wherein the quick detachment mechanism comprises a radialprojection at the inner end of the spindle, which projection can beretracted to enable the spindle to be inserted in or withdrawn from themounting bracket.
 14. A wheel hub as claimed in claim 1, wherein thefirst pin or pins have square end profiles which engage between splineson the splined surfaces.
 15. A wheel hub as claimed in claim 1, whereinthe second pin or pins have end profiles with one square face and oneramp face which engage between splines on the splined surfaces, so thatthe square face prevents rotation of the sleeve in one rotationaldirection relative to the spindle and the ramp face allows rotation inthe opposite rotation direction.
 16. A wheel hub as claimed in claim 1,wherein the first pin or pins are diametrically opposite, referred tothe spindle axis to the second pin or pins.
 17. A wheel hub as claimedin claim 1, wherein the body on the sleeve has radially extendingpassages communicating with the recess and the pins are radially movablepins which can move in and out of the recess to engage, one at a time,with the splined surface.
 18. A wheel hub as claimed in claim 17,wherein the radially movable pins have lateral lugs which engage in camtracks inside the selector so that movement of the selector in onerotational direction extends the first pins and movement in the oppositerotational direction extends the second pins.
 19. A wheel hub as claimedin claim 1, wherein the body on the sleeve comprises a radially movableslide plate moving between two fixed parallel slide guides such that theplate can move radially but cannot rotate relative to the guides, therecess being provided in the slide plate and the pins being formedintegrally with the plate at opposite regions of the circumference ofthe recess.
 20. A wheel hub as claimed in claim 19, wherein leaf springsmounted internally on the selector bias the opposite ends of the slideplate and the slide plate ends and the leaf springs are designed so thatmovement of the selector in each direction causes the leaf springs toride over a nose on the slide plate so that the selector is held in oneor other end position until the selector is manually operated to adifferent position.
 21. A wheel hub as claimed in claim 1, wherein thereare two first pins and two second pins.
 22. A wheel hub as claimed inclaim 1, wherein the hub is attached to a wheelchair.
 23. A wheel hub asset forth in claim 22, wherein the hub has attached thereto a wheel.